JPH0877972A - Fluorescent lamp, its lighting device, light source equipment using this, and liquid crystal display device - Google Patents

Abstract

PURPOSE: To provide a fluorescent lamp, in which mercury and xenon are sealed and a better luminous flux starting properly and better luminous efficiency in comparison with a fluorescent lamp in which mercury and argon are sealed are provided, its lighting device, light source equipment, and a liquid crystal display device. CONSTITUTION: A cold cathode 4 is arranged in the end part of a bulb 2 in which a phosphor coating 3 is formed on the inside surface, and in the bulb 2, mercury gas and xenon gas are sealed, a cross sectional area of a discharge space is set to 20mm<2> or less, and the current density of a lamp is set to 0.75mA/mm<2> or less. As mercury gas and xenon gas are sealed inside the bulb 2, an excellent luminous flux rising property at a start is provided while the lamp can be turned on in a good luminous efficiency area.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small fluorescent lamp filled with mercury and xenon gas, a lighting device for pulse-lighting this lamp, a light source device using the same, and a liquid crystal display device.

[0002]

2. Description of the Related Art For example, a small-sized cold cathode fluorescent lamp is used as a backlight of a liquid crystal display device or a display pointer of various meters. Explaining a specific example, one kind of cold cathode fluorescent lamps used as a light source of a backlight of a liquid crystal display device has a bulb inner diameter of 2 mm and a distance between electrodes of 90 mm.
Argon Ar gas of about a certain degree is enclosed, and a phosphor coating is formed on the inner surface of the bulb. When a high frequency voltage is applied between a pair of cold cathodes sealed at both ends of the bulb,
A discharge is generated in the bulb, and this discharge causes the mercury to
It emits 85 nm and 254 nm ultraviolet rays, which excite the phosphor to emit visible light. At this time, the lamp current is 5 mA and the brightness is 22000 cd / m ² .

However, the above-mentioned cold cathode fluorescent lamp is
It is a low-pressure mercury lamp that uses mercury as a light-emitting substance and argon as a rare gas. Evaporated mercury atoms emit ultraviolet rays of 185 nm and 254 nm due to ionization and excitation action. Therefore, the luminous efficiency is the vapor pressure of mercury. Depends on. Therefore, when the lamp power is low and the bulb temperature is low, the luminous flux is low because the mercury vapor pressure is low, and the luminous flux rising characteristics at the start are not good. That is, when the ambient temperature is low, for example, the lamp current is 1 mA and the brightness is 5 mA.
It becomes 000 cd / m ² and there is a problem that the luminous flux rises slowly at the time of starting.

It is known that a xenon rare gas discharge lamp is effective as a measure against such a low temperature starting in place of the cold cathode low pressure mercury lamp. A xenon rare gas discharge lamp is a lamp in which xenon or a rare gas mainly composed of xenon is enclosed in a bulb, and a phosphor coating mainly formed on the inner surface of a bulb of ultraviolet rays emitted from xenon and having wavelengths of 147 nm and 172 nm. Is converted into visible light, and this visible light is emitted to the outside of the arc tube.

This type of xenon rare gas discharge lamp does not use mercury and the xenon gas is not easily affected by temperature changes, and therefore has stable temperature characteristics and is used in an environment with a low ambient temperature. However, there is an advantage that the luminous flux rising characteristics are excellent.

[0006]

However, when the lamp is lit stably and the bulb temperature rises, the higher the temperature, the more the lamp in which mercury is enclosed promotes the evaporation of mercury, and the mercury emits more ultraviolet rays. Therefore, the luminous flux is increased and the luminous efficiency can be expected to be improved as compared with the lamp in which the xenon gas is sealed. Therefore, the mercury-filled fluorescent lamp is more advantageous during stable lighting of the lamp.

That is, a rare gas discharge lamp filled with xenon is effective at low temperature starting, and a fluorescent lamp filled with mercury is more advantageous when the temperature of the bulb becomes higher than a predetermined temperature.

As a compromise, there is a so-called mercury + xenon type fluorescent lamp in which xenon or a rare gas mainly containing xenon is filled in place of the argon instead of the conventional mercury + argon filled type fluorescent lamp. Conceivable.

In this way, the rise of the luminous flux at the time of low temperature starting can be quickly raised by the action of xenon, and the luminous flux during stable lighting can be expected to emit the vaporized mercury, so that the mercury + argon sealed type is used. Compared with a fluorescent lamp, the luminous flux rising characteristics at the time of starting are superior, and the luminous flux is increased compared with a xenon rare gas discharge lamp, so that the luminous efficiency is improved.

However, in the case of a mercury + xenon sealed type fluorescent lamp, when the temperature exceeds a predetermined temperature, the luminous flux tends to be lower than that of the mercury + argon sealed type fluorescent lamp.

Therefore, the inventors of the present invention can use a mercury + xenon-encapsulated fluorescent lamp having an excellent start-up characteristic only when the bulb temperature is low, as compared with a mercury + argon-encapsulated fluorescent lamp. It was speculated that it could be used in an efficient range.

The present invention has been made in view of the above circumstances, and its purpose is to provide a mercury which is superior in luminous flux rising characteristics for starting and superior in luminous efficiency as compared with a mercury + argon sealed type fluorescent lamp. An object of the present invention is to provide a + xenon-encapsulated type fluorescent lamp, its lighting device, a light source device using the same, and a liquid crystal display device.

[0013]

The invention of claim 1 [SUMMARY OF] includes a light-emitting tube bulb cross-sectional area of 20 mm ² or less of the discharge space, the rated current density within the valve occurs a 0.75 mA / mm ² or less of the discharge Means, a rare gas containing mercury and at least xenon, which is enclosed in the bulb and emits ultraviolet rays by the discharge, and an ultraviolet ray emitted from the mercury and xenon gas, which is provided inside the bulb and emits light. And a phosphor coating.

Here, the means for generating electric discharge in the bulb may be a pair of cold cathodes sealed in the bulb, one internal cold cathode and one external electrode, or an external electrode. May be only. Further, the rare gas may contain at least xenon, and other rare gas such as neon may be mixed with xenon. In short, xenon gas may be sealed in the range of 30 to 100% as the rare gas. Further, the lamp may have an aperture shape that emits light in a specific direction.

According to a second aspect of the invention, the pressure of the rare gas filled is 20.
0 Torr or less, of which the filling pressure of xenon gas is 2
It is characterized by being 0 Torr or more. The invention of claim 3 is characterized in that when the discharge space of the arc tube bulb has a circular cross section, the inner diameter is 5 mm or less.

According to a fourth aspect of the present invention, the cross-sectional area of the discharge space is 2
An arc tube bulb of 0 mm ² or less, a means for generating an electric discharge in the bulb, a rare gas containing mercury and at least xenon, which is enclosed in the bulb and emits ultraviolet rays by the electric discharge, and is provided inside the bulb. A fluorescent lamp including a phosphor coating that emits light by receiving ultraviolet rays emitted from the mercury and xenon gas, and a lighting means for lighting the fluorescent lamp at a current density of 0.75 mA / mm ² or less. It is a fluorescent lamp lighting device characterized by having.

According to a fifth aspect of the invention, the cross-sectional area of the discharge space is 2
An arc tube bulb of 0 mm ² or less, a means for generating an electric discharge in the bulb, a rare gas containing mercury and at least xenon, which is enclosed in the bulb and emits ultraviolet rays by the electric discharge, and is provided inside the bulb. And a fluorescent film that emits light upon receiving ultraviolet rays emitted from the mercury and xenon, and a fluorescent lamp having a current density of 0.10 mA / mm ² or more and 0.45 mA / mm.
A fluorescent lamp lighting device, comprising: a lighting means that lights at ² or less.

The invention of claim 6 is characterized in that the inner diameter of the arc tube bulb of claim 5 is 1.5 mm or more and 2.5 mm or less. The invention of claim 7 relates to claim 1 to claim 3.
2. A fluorescent lamp lighting device, comprising: the fluorescent lamp according to any one of 1 to 4; and a pulse voltage supply device that applies a pulse voltage having a rest period to the fluorescent lamp.

According to the invention of claim 8, the pulse voltage applied from the pulse voltage supply device to the fluorescent lamp with a rest period has a frequency of 30 kHz or more and 80 kHz or less and a duty ratio of 2% or more, It is a fluorescent lamp lighting device characterized by being 50% or less.

The invention of claim 9 comprises the fluorescent lamp lighting device according to any one of claims 4 to 8 and a light source device body incorporating the fluorescent lamp lighting device. It is a light source device.

An invention according to claim 10 is the fluorescent lamp lighting device according to any one of claims 4 to 8, and a liquid crystal display device body incorporating the fluorescent lamp lighting device.
A liquid crystal display device comprising:

[0022]

As described above, the inventors of the present invention have determined that a mercury + xenon-enclosed type fluorescent lamp, which is advantageous in the luminous flux rising characteristic of starting, has a better lamp efficiency than a mercury + argon-enclosed type fluorescent lamp. When attempting to use the lamp, paying attention to the fact that it is effective to use it under conditions where the bulb temperature is low, and various investigations were made on the relationship between the lamp current density and the luminous efficiency.

Normally, the bulb temperature will vary depending on the ambient temperature as well as the electrical energy input to the lamp. The electrical energy input to the lamp is related to the current density of the lamp. That is, if the current density of the lamp during stable lighting is low, the temperature of the arc tube bulb will also be low.

In a mercury + argon sealed type fluorescent lamp, the luminous flux increases as the current density of the lamp is increased.
On the other hand, the mercury + xenon-filled type fluorescent lamp has a large luminous flux at the time of starting, but even if the bulb temperature is changed by changing the current density, the vapor pressure of xenon does not change so much. The rate of increase is small. Therefore,
At a low bulb temperature, the luminous flux is higher than that of a mercury + argon sealed type fluorescent lamp. That is, a phenomenon occurs in which the luminous efficiency of the lamp is reversed.

Therefore, the present inventors have found through various experiments that the luminous efficiency of the mercury + xenon-filled type fluorescent lamp is more advantageous than that of the mercury + argon-filled type fluorescent lamp.

As a result, as described in claim 1, the rated current density of the lamp may be 0.75 mA / mm ² or less, and the cross-sectional area of the discharge space may be 20 mm ² or less. When the current density of the lamp exceeds 0.75 mA / mm ² , the luminous efficiency of the mercury + xenon-filled type fluorescent lamp becomes lower than that of the mercury + argon-filled type fluorescent lamp.

If the cross-sectional area of the discharge space exceeds 20 mm ² , the electron temperature is lowered and the self-absorption of xenon is increased, so that the efficiency is lower than that of the mercury + argon sealed type fluorescent lamp.

According to the second aspect of the invention, since the encapsulation pressure of xenon is set to 20 Torr or more, xenon is molecularly emitted and emits ultraviolet rays of 172 nm on the long wavelength side.
Efficiency is improved.

According to the third aspect of the present invention, when the discharge space has a circular cross-sectional shape, if the inner diameter is set to 5 mm or less, the self-absorption of xenon does not increase, and compared with a mercury + argon sealed type fluorescent lamp. And efficiency is improved.

According to the invention of claim 4, the same operation as that of the invention of claim 1 improves the luminous efficiency as compared with the fluorescent lamp of the mercury + argon enclosed type. According to the invention of claim 5, the current density is 0.10 to 0.45 mA / mm.
^{Since the} lamp is turned on in the range of ² , it is a more preferable range. That is, when the current density is used at 0.45 mA / mm ² or less, the efficiency is improved by 130% or more as compared with the conventional mercury + argon-filled type fluorescent lamp, which is a significant difference from the conventional one. In addition, the current density is 0.1
If it is less than 0 mA / mm ² , the amount of light emission is small and the brightness is low.

According to the sixth aspect of the invention, since the inner diameter of the arc tube bulb is in the range of 1.5 to 2.5 mm, it can be used in an efficiency range of 95% or more of the maximum efficiency. According to the invention of claim 7, since the fluorescent lamp of the mercury + xenon sealed type is pulse-lit, the light intensity is increased and further improvement in efficiency can be expected.

According to the invention of claim 8, the fluorescent lamp has a frequency of 30 to 80 kHz and a duty ratio of 2 to 5.
Since the lighting is performed with the pulse voltage in the range of 0%, the efficiency becomes very good.

According to the ninth aspect of the present invention, it is possible to provide a light source device excellent in startability and efficiency. According to the invention of claim 10, it is possible to provide a liquid crystal display device which is excellent in startability and efficiency.

[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the first embodiment shown in FIGS. FIG. 1 shows the structure of a mercury + xenon sealed cold cathode fluorescent lamp and its lighting device. Reference numeral 1 is a mercury + xenon sealed cold cathode fluorescent lamp, 10 is a pulse voltage application device including a pulse inverter, and 11 Is a current limiting means.

The fluorescent lamp 1 has a long and narrow needle-shaped arc tube bulb 2, which has an inner diameter of 2.00 mm, for example.
Therefore, it has a cross-sectional area of 3.14 mm ² and is formed in a straight tube shape from lead glass having a length of 130 mm. On the inner surface of the bulb 2, ultraviolet rays having wavelengths of 185 nm and 254 nm emitted by mercury, and wavelengths of 147 nm and 172 emitted by xenon are emitted.
A phosphor coating 3 made of a phosphor that emits light with an ultraviolet ray of nm, for example, a three-wavelength emitting phosphor is formed. The three-wavelength light emitting phosphor is, for example, Y ₂ O ₃ as a red phosphor:
Eu, LaPO ₄ : Ce, Tb is used as a green phosphor, and BaMgAl ₁₄ O ₂₃ : Eu is used as a blue phosphor.

At both ends of the bulb 2 in the longitudinal direction, cold cathodes 4 and 4 having a distance between electrodes (discharge length) of 5 mm or more, for example 90 mm, are sealed. Each of the cold cathodes 4 and 4 is configured by joining a rod-shaped electrode body 6 to an electrode shaft 5 that also serves as a lead wire, and the electrode body 6 has a wire diameter of 0.5 mm and a length of 10 mm.
It is made of mm nickel wire. The electrode shaft 5
Is a sealing wire 7 made of a metal having a coefficient of thermal expansion similar to that of glass.
And the sealing wire 7 is sealed to the sealing portion 8 at the end of the valve 2. The sealing wires 8 and 8 are connected to external lead wires 9 and 9, respectively.

The arc tube bulb 2 is filled with a predetermined amount of mercury and a predetermined pressure of xenon Xe or a rare gas mainly containing xenon. The total filling pressure of noble gas is 20
It is less than 0 Torr, and the partial pressure of xenon enclosed is more than 20 Torr. In the case of the present embodiment, a mixed gas in which neon Ne is mixed with xenon Xe is used, and for example, xenon Xe 60% and neon Ne 40%,
The total filling pressure is 50 Torr.

The cold cathode fluorescent lamp 1 having such a structure is
It is connected to a pulse voltage application device 10 such as the pulse inverter shown in FIG. 1 and a current limiting means 11.
The pulse voltage applying device 10 is adapted to apply a pulse having a rest period, that is, a pulse voltage having a predetermined duty ratio, between the cold cathodes 4 and 4. In this case, the pulse frequency is 30 to 80 kHz and the duty ratio τ (a /
a + b) is 2% or more and 50% or less.

In the case of such a cold cathode fluorescent lamp 1 containing mercury and xenon, the pulse voltage applying device 10 is used.
Also, the current limiting means 11 allows the lamp current IL of 1.2 mA to flow during the stable lighting of the lamp. The current density of the lamp in this case is 0.38 mA / mm
It becomes ² .

In the cold cathode fluorescent lamp 1, the current density during stable lighting of the lamp is in the range of 0.75 mA / mm ² or less, and the sectional area of the bulb 2 is in the range of 20 mm ² or less. The luminous efficiency is higher than that of the cold cathode fluorescent lamp in which the structure of mercury and argon gas is enclosed.

That is, a cold cathode fluorescent lamp 1 of the above structure containing mercury and xenon, a cold cathode xenon rare gas discharge lamp of the same structure, and a cold cathode fluorescent lamp of the same structure containing mercury and argon. The relationship between the current density (mA / mm ² ) and the total luminous flux of the light emitted from the lamp was measured, and the characteristics shown in FIG. 2 were obtained.

In the case of the cold cathode fluorescent lamp 1 containing mercury and xenon, when the current density (mA / mm ² ) is gradually increased as shown by the characteristic A shown by the solid line, the current density is up to about 0.4 mA / mm ^2. The luminous flux increases, and when the current density (mA / mm ² ) is further increased, the luminous flux is saturated and the characteristics tend to be curved.

On the other hand, in the case of a xenon rare gas discharge lamp, the current density (mA
/ Mm ² ) is gradually increased, the current density becomes approximately 0.2.
There was a tendency that the luminous flux increased sharply up to mA / mm ² , and when the current density (mA / mm ² ) was further increased, the luminous flux was saturated and rather decreased. However, the xenon rare gas discharge lamp has a disadvantage that the total luminous flux is lower than that of the cold cathode fluorescent lamp 1 of the mercury + xenon sealed type.

On the other hand, in the case of the mercury + argon sealed type cold cathode fluorescent lamp, when the current density (mA / mm ² ) is gradually increased, the luminous flux increases almost linearly as indicated by the characteristic C shown by the broken line. To do.

As can be seen from FIG. 2, the characteristic A and the characteristic C intersect with each other, and in the region where the current density (mA / mm ² ) is lower than this intersection, the cold cathode fluorescent lamp 1 of the mercury + xenon enclosure type is used. The luminous flux exceeds that of the cold cathode fluorescent lamp of the mercury + argon sealed type. That is, characteristic A
The current density is 0.75 mA / mm ² at the intersection of the characteristic C and the characteristic C. Therefore, in the region where the current density is 0.75 mA / mm ² or less, the mercury + xenon sealed cold cathode fluorescent lamp 1
Can be lit in a brighter state than the cold cathode fluorescent lamp of the mercury + argon sealed type.

Next, the present inventors have found that the current density (mA / mm
² ) and the luminous efficiency of the lamp were investigated. The result is shown in FIG. In the case of the mercury + xenon sealed type cold cathode fluorescent lamp 1, as shown by the solid line A, the current density (mA / mA /
When the mm ² ) is gradually increased, the luminous efficiency gradually decreases. On the other hand, in the case of a xenon rare gas discharge lamp, as indicated by the one-dot chain line B, as the current density (mA / mm ² ) is gradually increased, the luminous efficiency decreases in a hyperbolic manner. In the case of a mercury + argon sealed type cold cathode fluorescent lamp,
As indicated by a broken line C, the luminous efficiency increases almost linearly as the current density (mA / mm ² ) is gradually increased. Also in this case, at the intersection of the characteristic A and the characteristic C, that is, in a region smaller than the current density of 0.75 mA / mm ² , the mercury + xenon sealed cold cathode fluorescent lamp 1 is a mercury + argon sealed cold cathode fluorescent lamp. It can be confirmed that the luminous efficiency is improved as compared with the lamp.

Furthermore, the present inventors investigated the relationship between the inner diameter of the arc tube bulb and the luminous efficiency of the lamp. The results are shown in FIG. 4, and from FIG. 4, the luminous efficiency of the cold cathode fluorescent lamp 1 of the mercury + xenon enclosure type exceeds that of the cold cathode fluorescent lamp of the mercury + argon enclosure type when the inner diameter of the bulb is 5 mm or less. It has been confirmed that this is the case. this is,
If the inner diameter of the valve is 5 mm or less, 147 of xenon gas
It is considered that the self-absorption at nm and 172 nm is reduced and the light output is increased.

Setting the inner diameter of the arc tube to 5 mm or less is sufficient if the cross-sectional shape of the discharge space is circular, but if the cross-sectional shape of the discharge space is not circular, considering the cross-sectional area of the discharge space. Good. FIG. 5 shows the relationship between the cross-sectional area of the discharge space in the arc tube and the luminous efficiency of the lamp. From the figure, if the cross-sectional area of the discharge space is set to 20 mm ² or less, the mercury + xenon sealed type cooling It was confirmed that the cathode fluorescent lamp 1 has improved luminous efficiency as compared with the cold cathode fluorescent lamp of the mercury + argon sealed type. It is considered that this is because the self-absorption of the xenon gas is reduced as described above and the decrease of the electron temperature is suppressed. If the cross-sectional area is 1 mm ² or less, the current density becomes excessive, the cumulative ionization increases, and the heat loss from the wall of the arc tube increases as a ratio, resulting in a decrease in efficiency.

From the above experimental results, the cold cathode fluorescent lamp 1 of the mercury + xenon sealed type has a current density of 0.75 mA / mm ² or less during stable lighting of the lamp and a cross-sectional area of the discharge space of 20 mm ^2. Below, that is, if the inner diameter of the bulb 2 is set to 5 mm or less, the luminous efficiency will be higher than that of a cold cathode fluorescent lamp in which mercury and argon gas of the same structure are sealed, and therefore, the luminous flux rises at the time of starting and the luminous efficiency of It can be used under excellent conditions.

Furthermore, in the cold cathode fluorescent lamp 1 of the mercury + xenon sealed type, the current density during stable lighting of the lamp is 0.75 mA / mm ² or less, and the cross-sectional area of the discharge space is 20 mm ² or less, that is, If the inner diameter of the bulb 2 is set to 5 mm or less, the luminous efficiency will be higher than that of a xenon rare gas discharge lamp having the same structure, so that the lamp can be used under the condition that the luminous flux rises at the time of starting and the luminous efficiency is excellent.

A more preferable range of use is that the current density of the lamp is 0.10 mA / mm ² or more and 0.45 mA / mm ^2.
It is desirable to light at mm ² or less. That is, when the current density is 0.45 mA / mm ² or less, the efficiency of 130% or more can be obtained as compared with the conventional mercury + argon sealed type fluorescent lamp, and the current density is 0.30 mA.
If it is less than / mm ² , the efficiency of 200% or more can be obtained as compared with the conventional mercury-argon-encapsulated type fluorescent lamp, so that a significant difference is produced as compared with the conventional one.

When the current density is 0.75 mA / mm ² or less, the efficiency is improved, but the current density is 0.10 mA / mm ^2.
When it is less than mm ² , the luminous flux is reduced and the brightness is 22000 cd.
/ M ² or less and the amount of light emission decreases, which is not preferable.

Then, the current density of the lamp is set to 0.10 mA.
In the case of lighting at / mm ² or more and 0.45 mA / mm ² or less, the inner diameter of the arc tube bulb should be 1.5 mm or more and 2.5 mm or less. As can be understood from FIG. 4, the mercury + xenon enclosed type lamp shows the maximum efficiency when the inner diameter of the bulb is 2 mm. If the maximum efficiency is used in the range of 95% or more, it is recognized as an effective range of use. Therefore, if the range of the maximum efficiency of 95% or more is found from the characteristics of Fig. 4, the valve inner diameter is 1.5 mm or more, and 2 It can be confirmed that it should be less than 0.5 mm. This indicates that when converted to the cross-sectional area of the discharge space, the cross-sectional area should be 1.8 mm ² or more and 5 mm ² or less.

Further, when the cold cathode fluorescent lamp 1 of the mercury + xenon sealed type is pulse-lit, radiation is generated due to recombination of xenon ions during the pulse rest period, and so-called afterglow occurs. Emits ultraviolet rays, which increases the luminous efficiency. In this case, the pulse frequency is 40-80 kH
z, for example, 60 kHz, and its duty ratio τ
(A / a + b) is 2% or more and 20% or less, for example, 4 to 1
0% is desirable.

The results of examining the frequency and the duty ratio are shown in FIGS. 6 to 8. FIG. 6 is a characteristic diagram showing the relationship between frequency and luminous efficiency, and each characteristic shows the case where the duty ratio τ is changed to 10%, 50%, and 75%. From this figure, it can be seen that the efficiency exhibits a peak value when the frequency is approximately 60 kHz regardless of the duty ratio. And in each characteristic, the range where the efficiency of 90% or more of the peak efficiency is obtained is the range of the frequency of 30 kHz to 80 kHz, that is, good efficiency can be obtained if the frequency is regulated to the range of 30 kHz to 80 kHz. I understand.

Further, FIG. 7 shows the duty ratio τ (a / a +
The luminous efficiency when b) is changed is shown. In the range where 90% or more of the peak efficiency is obtained from this characteristic, the duty ratio is preferably 2% or more and 50% or less, and preferably 4% or less.
The range of 20% is preferable. The reason for this is as follows.
That is, when a lamp containing mercury and xenon is pulse-lit, the ultraviolet ray output as shown in FIG. 8 is obtained. That is, when the pulse is applied, the UV output of the I zone is generated, and the UV output of the II zone is generated during the rest period of the pulse. This is due to the property of xenon gas, and xenon emits radiation due to recombination of xenon ions during the pulse rest period, so-called afterglow occurs. This afterglow emits ultraviolet light during the pulse rest period. Therefore, the UV output of the I zone during the application of the pulse is the UV emitted from both mercury and xenon, and the UV output of the II zone during the pulse rest period is mainly the output due to the afterglow of xenon.

In order to increase the luminous efficiency, the ultraviolet light output in the II zone during the pulse rest period may be increased, that is, the emission of xenon may be used. Therefore, the longer rest period is advantageous. From this point of view, it is preferable to make the duty ratio relatively long, but 20% or less, and if the duty ratio is 20% or less, an efficiency of 90% or more of the peak efficiency can be expected. However, the duty ratio is 20%
The circuit described below is practically unrealizable, and the duty ratio is actually 50% or less.

If the duty ratio is too low, the emission of mercury cannot be expected during pulse application, and in order to utilize the mercury emission, it is necessary to make the duty ratio at least 2% or more.

As a result, the duty ratio is 50% when the duty ratio is 2% or more.
% Or less, preferably 4 to 20%. By the way, the total filling pressure of xenon or a rare gas mainly containing xenon needs to be 200 Torr or less. If the total filling pressure of rare gas is set to 200 Torr or more,
The self-absorption of the rare gas increases and the efficiency decreases. Moreover, since this type of lamp is a thin bulb, there is a fear of damage due to insufficient strength. Therefore, the total filling pressure of the rare gas is 20
0 Torr or less is good.

Further, even if the filling pressure of the whole rare gas is 200 Torr or less, the partial pressure of xenon is set to 20 Torr or more. The reason for this is as follows. In other words, xenon emits 147 nm ultraviolet light and 172 nm ultraviolet light,
UV radiation at 147 nm is predominantly atomic emission, whereas UV radiation at 172 nm is predominantly molecular emission. When the gas pressure of xenon is low, for example, about 10 to 20 Torr, atomic emission occurs and ultraviolet radiation at 147 nm increases. However, the phosphor generally used for the fluorescent lamp has been developed so that the sensitive ultraviolet region thereof is adapted to the ultraviolet ray (254 nm) emitted from mercury, and is in the ultraviolet region on the relatively long wavelength side. In other words, it is more advantageous to emit ultraviolet light of 172 nm, which is on the longer wavelength side than that of molecular emission, than to emit ultraviolet light of 147 nm by atomic emission. Therefore, it is better for xenon to emit molecular light rather than atomic light emission. Therefore, it is advantageous to set the gas pressure for filling xenon to a high pressure of 20 Torr or more.

The high-frequency voltage waveform to be applied to the lamp is not limited to the pulse waveform shown in FIG. 8 and is as shown in FIGS. 9A and 9B as the second and third embodiments, respectively. It may be a voltage waveform. Also in the case of these voltage waveforms, the duty ratio is represented by (a / a + b).

The cold cathode fluorescent lamp 1 of the above-mentioned mercury + xenon sealed type is, for example, as shown in FIG.
0 and the backlight of the liquid crystal display device shown in FIG.

In the liquid crystal display device shown in FIG. 10 and FIG. 11, a light diffusing light guide plate 21 is arranged on the back surface of the liquid crystal display plate 20 so as to be superposed, and the light diffusing light guide plate 21 is made of milky white acrylic resin or the like. The side surfaces in three directions except the lower surface and one side surface are surrounded by the casing 22. The casing 22 has a reflection surface 23 on the inner surface. On the open surface formed on one side of the casing 32, the cold cathode fluorescent lamp 1 of the mercury + xenon enclosure type as a light source is arranged.

The cold cathode fluorescent lamp 1 is housed in a cylindrical reflector 25 connected to face an open surface formed on one side of the casing 22. The inner surface of the cylindrical reflector 25 forms a reflecting surface 26, and the lamp 1 is housed in the reflector 25 with its lamp axis aligned with the center line of the reflector 25. The cylindrical reflector 25 is the case
A side wall facing the open surface formed on one side of the sing 22 is opened so that all the light emitted from the rare gas discharge lamp 1 is introduced to one side of the light diffusion light guide plate 21. ing.

The cold cathode fluorescent lamp 1 shown in FIG.
A pulse voltage is applied from the pulse voltage applying device 10 shown in FIG. 1 to turn on the light, and the light emitted from the lamp 1 is reflected by the inner reflection surface 26 of the reflector 25, and the light diffusion light guide plate. 21 is introduced on one side. The light introduced into this light diffusion light guide plate 21 is
The light is diffused inside and reflected by the reflection surface 23 formed on the inner surface of the casing 22, and is directed toward the upper surface of the light diffusion light guide plate 21. For this reason, the upper surface of the light diffusing light guide plate 21 has a substantially uniform brightness over the entire surface, and the liquid crystal display plate 20 arranged so as to overlap this surface is evenly illuminated from the rear surface.

In such a liquid crystal display device, the startup characteristic of the cold cathode fluorescent lamp 1 of the mercury + xenon enclosure type at the time of starting is good, and moreover, the luminous efficiency during stable lighting is good, so that it is used as a liquid crystal display device. Improves starting performance and display performance during use.

In the above embodiment, the cold cathode fluorescent lamp 1 of the mercury + xenon sealed type has the cold cathodes 4 and 4 sealed inside both ends of the bulb 2, but the means for maintaining the discharge is not limited to this. For example, the cold cathode 4 may be sealed at one end of the bulb 2 and an external electrode may be provided outside the bulb so that discharge can be generated in the bulb between the cold cathode 4 inside and the external electrode.

Further, a mercury + xenon-encapsulated type fluorescent lamp 30 shown in FIGS. 12 and 13 as a fifth embodiment.
As described above, a pair of external electrodes 32, 32 facing each other in the form of strips are provided outside the valve 31, and these external electrodes 32, 32 are connected to the pulse voltage applying device 10 and the current limiting means 11. The discharge may be generated in the bulb 31. The valve 31
A predetermined amount of mercury and a predetermined pressure of xenon Xe or a noble gas containing xenon as a main component are enclosed within the above range. Further, on the inner surface of the bulb 31, a phosphor coating 33 having an absorption band for ultraviolet rays emitted from mercury and xenon Xe is formed.

Even in the external electrode type mercury + xenon sealed type fluorescent lamp 30 having such a structure, the current density during stable lighting of the lamp is set to 0.75 mA / mm ² or less,
And the cross-sectional area of the discharge space is 20 mm ² or less, that is, the valve
When the inner diameter of 1 is 5.0 mm or less, the starting characteristics are excellent and the luminous efficiency is higher than that of a fluorescent lamp in which mercury + argon gas of the same structure is sealed.

Further, the present invention is not limited to the fluorescent lamp used for the backlight of the liquid crystal display device, but may be a small-diameter fluorescent lamp as a self-luminous pointer used for various meters, for example.

Further, the xenon gas may be mixed with another noble gas such as argon, neon or krypton. In short, xenon is 3 as the noble gas.
It may be enclosed in the range of 0 to 100%.

Furthermore, the invention can be carried out even with an aperture fluorescent lamp in which the emission intensity in a specific direction is increased.
Further, the fluorescent lamp of the present invention may have a structure like the sixth embodiment shown in FIGS. 14 (A) and 14 (B).

In the lamp of the sixth embodiment shown in FIGS. 14A and 14B, the arc tube bulb is constructed by joining the lower cover glass 61 and the upper cover glass 62 to the upper and lower surfaces of the base glass 60. For example, a U-shaped bent groove 63 is formed in the base glass 60. Therefore, a U-shaped bent groove 63 is formed in the space surrounded by the base glass 60, the lower cover glass 61 and the upper cover glass 62. A discharge path 64 is formed. At both ends of the discharge path 64, a cold cathode 65 made of, for example, a nickel rod,
A cold cathode 65, 65 is connected to the pulse inverter 10 and the current limiting means 11. The frequency of the pulse inverter 10 is 30 to 80k.
A pulse voltage having a duty ratio of 2% or more and 50% or less is supplied at Hz. A phosphor coating (not shown) is formed on the inner surface of the discharge path 64. In the discharge path 64, mercury and
Xenon or a rare gas mainly composed of xenon is enclosed in the range of the above-mentioned conditions.

Even with a fluorescent lamp having such a structure,
If the current density during stable lighting of the lamp is 0.75 mA / mm ² or less, and the cross-sectional area of the discharge path 64 is 20 mm ² or less, the luminous flux startup characteristics at start-up are excellent and the lamp is used under conditions of excellent luminous efficiency. can do.

The seventh embodiment shown in FIGS. 15A and 15B may also be used. The lamp of the seventh embodiment shown in FIGS. 15A and 15B has a lower cover glass 71 and an upper cover glass 72 joined to the upper and lower surfaces of a base glass 70 constituting an arc tube bulb. The base glass 70 is formed with a large number of grooves 73 ... Which extend in the radial direction. Therefore, these base glass 70, lower cover glass 71, and upper cover glass 72
Discharge paths 74 extending in the radial direction are formed in a space surrounded by. The discharge paths 74 extending in the radial direction communicate with each other in the central portion of the base glass 70, and the cathode 75 serving as a common electrode is arranged in the central portion, and the discharge paths 74 extending in the respective radial directions. An anode 76, which is made of, for example, a nickel rod, is sealed at the tip of each. These cathode 75 and anode 76 ... Are respectively connected to a pulse inverter and current limiting means (not shown).

A phosphor coating (not shown) is formed on the inner surfaces of the discharge paths 74 ... Mercury and xenon or a rare gas mainly containing xenon are enclosed in the discharge paths 74 ... within the above-mentioned conditions. Has been done.

Even with a fluorescent lamp having such a structure,
The current density during stable lighting of the lamp is 0.75 mA / mm ² or less, and the cross-sectional area of each of the discharge paths 74 is 20 mm ²
If it is set as follows, it can be used under the condition that the luminous flux rising characteristic at the time of starting is excellent and the luminous efficiency is excellent.

Further, the lamp of the eighth embodiment shown in FIGS. 16A and 16B extends axially on the side wall of the cylindrical base glass 80 forming the arc tube bulb. Multiple discharge paths 81 of circular or other shape ...
Are arranged side by side in the circumferential direction, and cold cathodes 82, 82 made of, for example, nickel rods are sealed at both ends of these discharge paths 81.
Reference numerals 2 and 82 are connected to a pulse inverter and current limiting means (not shown).

A phosphor coating (not shown) is formed on the inner surface of each discharge path 81 ...
Is filled with mercury, xenon, or a rare gas mainly containing xenon within the range of the above-mentioned conditions.

Even with a fluorescent lamp having such a structure,
If the current density during stable lighting of the lamp is 0.75 mA / mm ² or less and the cross-sectional area of the discharge path 81 is 20 mm ² or less, the luminous flux startup characteristics at start-up are excellent and the lamp is used under conditions of excellent luminous efficiency. can do. From each of the embodiments shown in FIGS. 14 to 16, the cross-sectional shape of the discharge paths 64, 74, 81 may be circular, square, or other various shapes.

[0081]

As described above, according to the first aspect of the present invention, mercury is superior in the luminous flux rising characteristic at the time of starting and in luminous efficiency as compared with the conventional mercury + argon sealed type low pressure mercury lamp. It is possible to provide a + xenon-enclosed type fluorescent lamp.

According to the invention of claim 2, since the encapsulation pressure of xenon is set to 20 Torr or more, xenon is molecularly emitted and emits ultraviolet rays of 172 nm on the long wavelength side.
Efficiency is improved.

According to the invention of claim 3, when the cross-sectional shape of the discharge space is circular, if the inner diameter is set to 5 mm or less, the self-absorption of xenon does not increase, and compared with the mercury + argon sealed type fluorescent lamp. And efficiency is improved.

According to the invention of claim 4, the same operation as that of the invention of claim 1 improves the luminous efficiency as compared with the fluorescent lamp of the mercury + argon sealed type. According to the invention of claim 5, the current density is 0.10 to 0.45 mA / mm.
^{Since the} lamp is turned on in the range of ² , it is a more preferable range. That is, when the current density is used at 0.45 mA / mm ² or less, the efficiency is improved by 130% or more as compared with the conventional mercury + argon-filled type fluorescent lamp, which is a significant difference from the conventional one. In addition, the current density is 0.1
If it is less than 0 mA / mm ² , the amount of light emission is small and the brightness is low.

According to the invention of claim 6, since the inner diameter of the arc tube bulb is in the range of 1.5 to 2.5 mm, it can be used in the efficiency range of 95% or more of the maximum efficiency. According to the invention of claim 7, since the fluorescent lamp of the mercury + xenon sealed type is pulse-lit, the light intensity is increased and further improvement in efficiency can be expected.

According to the invention of claim 8, the fluorescent lamp has a frequency of 30 to 80 kHz and a duty ratio of 2 to 5.
Since the lighting is performed with the pulse voltage in the range of 0%, the efficiency becomes very good.

According to the ninth aspect of the present invention, it is possible to provide a light source device excellent in startability and efficiency. According to the invention of claim 10, it is possible to provide a liquid crystal display device which is excellent in startability and efficiency.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a mercury + xenon-enclosed cold cathode fluorescent lamp according to a first embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a relationship between current density and relative total luminous flux.

FIG. 3 is a characteristic diagram showing a relationship between current density and relative luminous efficiency.

FIG. 4 is a characteristic diagram showing a relationship between a bulb inner diameter and relative luminous efficiency.

FIG. 5 is a characteristic diagram showing the relationship between the cross-sectional area of the discharge space and the relative luminous efficiency.

FIG. 6 is a characteristic diagram showing the relationship between frequency and luminous efficiency.

FIG. 7 is a characteristic diagram showing the relationship between duty ratio and luminous efficiency.

FIG. 8 is a characteristic diagram showing changes in pulse application timing and ultraviolet ray output.

9 (A) and (B) are respectively the second of the present invention.
FIG. 6 is a diagram showing different voltage waveforms of the example of FIG.

FIG. 10 is an exploded perspective view of a liquid crystal display device using a cold cathode fluorescent lamp of FIG. 1 as a backlight source according to a fourth embodiment of the present invention.

FIG. 11 is a cross-sectional view of the liquid crystal display device.

FIG. 12 is a sectional view of a mercury + xenon-filled type fluorescent lamp according to a fifth embodiment of the present invention.

FIG. 13 is a sectional view of the discharge lamp.

14A and 14B show a sixth embodiment of the present invention, FIG. 14A is an exploded perspective view of the entire fluorescent lamp, and FIG. 14B is a sectional view taken along the line AA of FIG.

15A and 15B show a seventh embodiment of the present invention, wherein FIG. 15A is a plan view of the entire fluorescent lamp, and FIG. 15B is a sectional view taken along the line AA in FIG. 15A.

16A and 16B show an eighth embodiment of the present invention, wherein FIG. 16A is a sectional view of the entire fluorescent lamp, and FIG. 16B is a sectional view taken along the line AA of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Mercury + xenon sealed type cold cathode fluorescent lamp 2 ... Bulb 3 ... Phosphor coating 4 ... Cold cathode 10 ... Pulse voltage applying device 11 ... Current limiting means 20 ... Liquid crystal display plate 21 ... Light diffusion light guide plate 25 ... Reflector 30 ... Mercury + xenon sealed type fluorescent lamp 31 ... Bulb 32 ... External electrode 33 ... Phosphor coating.

Claims (10)

[Claims] 1. A light emitting tube bulb cross-sectional area of 20 mm ² or less of the discharge space, and means for the rated current density in the bulb a discharge is generated in the following 0.75 mA / mm ^2, enclosed within the valve, A rare gas containing mercury and at least xenon that emits ultraviolet rays by the discharge, and a phosphor coating that is provided inside the bulb and emits light by receiving ultraviolet rays emitted from the mercury and xenon gas. And a fluorescent lamp. 2. The fluorescent lamp according to claim 1, wherein the filling pressure of the rare gas is 200 Torr or less, and the filling pressure of the xenon gas is 20 Torr or more. 3. The fluorescent lamp according to claim 1, wherein the inner diameter of the arc tube bulb is 5 mm or less. 4. An arc tube bulb having a discharge space having a cross-sectional area of 20 mm ² or less, means for generating a discharge in the bulb, mercury contained in the bulb and emitting ultraviolet rays by the discharge, and at least xenon. A fluorescent lamp provided with a rare gas and a phosphor coating which is provided inside the bulb and emits light by receiving ultraviolet rays emitted from the mercury and xenon gas, and a fluorescent lamp having a current density of 0.75 mA / A fluorescent lamp lighting device, comprising: a lighting means that lights at a value of mm ² or less. 5. A discharge tube bulb having a discharge space having a cross-sectional area of 20 mm ² or less, means for generating a discharge in the bulb, mercury contained in the bulb and emitting ultraviolet rays by the discharge, and at least xenon. A fluorescent lamp provided with a rare gas and a phosphor coating which is provided inside the bulb and emits light when receiving ultraviolet rays emitted from the mercury and xenon gas, and a fluorescent lamp having a current density of 0.10 mA / mm ² or more,
A fluorescent lamp lighting device, comprising: a lighting unit that lights at 0.45 mA / mm ² or less. 6. The arc tube bulb has an inner diameter of 1.5 mm or more,
The fluorescent lamp lighting device according to claim 5, wherein the fluorescent lamp lighting device has a diameter of 2.5 mm or less. 7. The fluorescent lamp according to any one of claims 1 to 3, and a pulse voltage supply device for applying a pulse voltage having a rest period to the fluorescent lamp. Fluorescent lamp lighting device. 8. The pulse voltage having a rest period applied to the fluorescent lamp from the pulse voltage supply device has a frequency of 30 kHz or more and 80 kHz or less and a duty ratio of 2% or more and 50% or less. The fluorescent lamp lighting device according to claim 7, wherein: 9. A light source device comprising: the fluorescent lamp lighting device according to any one of claims 4 to 8; and a light source device main body incorporating the fluorescent lamp lighting device. 10. The method according to any one of claims 4 to 8.
2. A liquid crystal display device comprising: the fluorescent lamp lighting device according to claim 1; and a liquid crystal display device body incorporating the fluorescent lamp lighting device.